A rare waterspout formed off the coast of Hawaii yesterday (May 2), and was caught in several pictures and videos.

Waterspouts, tornadoes that touch on water, are not themselves made of water; they are funnel clouds that shoot down from storm clouds. This "tornado on water" touched down over the ocean off Ala Moana, a district of Honolulu.

In areas where intense funnel clouds commonly form over water -- the Florida Keys and the Adriatic Sea are two examples -- waterspouts will frequently form along a line of developing thunderstorms.

That was the case yesterday, as an intense lightning storm with heavy rains knocked out power for 60,000 residents, according to the Hawaiian Reporter. The heavy rains soaked Honolulu and triggered a flash flood warning.

Water Sprout
© Erik Vossman, www.alohaupdate.com
A similarly unusual weather event was also seen in the Bay Area earlier this year.

Waterspouts rarely cause damage, so they usually aren't rated on the Enhanced Fujita tornado damage scale.

Water Sprout_2
© Erik Vossman, www.alohaupdate.com
Most of the Earth's tornadoes touch down in the area of the United States known as Tornado Alley, bordered by the Dakotas to the north, the Gulf Coast to the south, the Rocky Mountains to the west and the Appalachian Mountains to the east. Southeast of Tornado Alley is Dixie Alley, home to the deadliest tornadoes.

In these areas, warm, moist Gulf of Mexico air collides with cool, northern air in the spring. But tornadoes can occur elsewhere and at other times of the year, including tornadoes in winter.

In Hawaii and California, which have different weather patterns than those in Tornado Alley, waterspouts or tornadoes are typically formed as instability in the atmosphere along a cold front meets channelized winds to generate swirling storms.